Yes, that Plugable one is what's in my 2009 iMac right now and it's working fine.
Before getting a new one it might be worth running through the instructions on flipping the active Bluetooth adaptor over again. I think if you have any previously paired devices then that can stop it choosing the new adaptor.
I updated the Quick Start page here http://www.espruino.com/Puck.js+Quick+Start#requirements a few days ago - I bought all of those Bluetooth adaptors to check. While yours isn't on that list, if it's broadcom and set up right I'd be amazed if it isn't going.
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